Semiconductor devices based on silicon carbide (SiC) benefit from the wide bandgap, high breakdown electric field, high thermal conductivity, chemical inertness and mechanical hardness of silicon carbide. One of the hurdles that impede to some degree the wide-scale introduction of SiC devices is the metallurgic interface between SiC and metals, which is more complex than that between metal and other semiconductor materials and which is part of ohmic contacts to SiC. Ohmic contacts provide unimpeded flow of charge carriers to and from doped regions in a semiconductor body to a metal terminal, when a bias voltage is applied across the ohmic contact. An ohmic contact is typically defined as an interface which has a linear and symmetric current voltage relationship at least within the limits of its intended use. Ohmic contacts to doped regions in silicon carbide are typically based on a metal silicide. Quality and stability of silicide contacts strongly depend on the process conditions under which the silicide contact is formed, on doping level and dopant type in the doped silicon carbide region, surface roughness, the polytype of the silicon carbide lattice and on whether the contact surface of the silicon carbide region is formed from silicon atoms (Si-face) or carbon atoms (C-face).
There is a need for a cost-competitive, reliable and easily applicable ohmic contact for silicon carbide devices.